Asymmetric catalysis is one of the most powerful methods for accessing a wide range of enantiomerically enriched compounds through the action of a chiral catalyst in a variety of asymmetric reactions. Highly promising candidates for asymmetric synthesis are transition metal complexes bearing chiral ligands. Despite the large number of chiral ligands employed in asymmetric synthesis, only a few have found a practical application in the manufacture of chiral molecules by the chemical and pharmaceutical industry.
Among these ligands, BINAP is one of frequently used chiral ligands. BINAP has been shown to be highly effective for many asymmetric reactions (Noyori and Takaya, Acc. Chem. Res., 1990, 23, 345; and Olkuma et al., Am. Chem. Soc., 1998, 120, 13529). Related axially dissymmetric ligands, such as MeO-BIPHEP and BIPHEMP have also been employed in a number of asymmetric reactions (Schmid et al., Pure & Appl. Chem., 1996, 68, 131; Foricher, Heiser and Schmid, U.S. Pat. No. 5,302,738; Michel, European Patent Application 0667350 A1; and Broger et al., PCT WO 92/16536). The structures for BINAP, BIPHEMP and MeO-BIPHEP are illustrated in FIG. 1.
FIG. 1.

Despite the extensive research in this area, there are still a variety of reactions in which only modest enantioselectivity has been achieved with these ligands. Thus, it remains highly desirable to develop novel chiral ligands which are selective and effective in a variety of asymmetric catalytic reactions, and are synthetically easily accessible.